1. Field of the Invention
This invention is related to angular velocity or rate sensors and more particularly to a novel technique based on the mechanics of fluid dynamic laminar flow.
2. Description of the Prior Art
A type of "fluidic" angular rate sensor known in the art is described by U.S. Pat. No. 3,500,691--Moore issued Mar. 17, 1970 according to which angular rate is sensed by the deflection of a laminar fluid jet which is discharged through a nozzle. The deflection of the jet stream is sensed downstream by thermistor elements which are positioned apart such that under conditions of no angular movement, the jet stream traverses between the sensing elements. A sleeve or shroud is incorporated around the jet nozzle and sensing means in order to reduce the effects of fluid shear or turbulent boundary layer which surrounds the discharging jet. The interaction of the discharging jet from its nozzle with the ambient fluid into which the jet proceeds results in a flow instability which interacts with the sensing means. In order to avoid a resultant noise signal from the sensing means, the sensing means are separated by a spacing which is larger than what could be considered the fluid jet diameter. This results in an angular rate "threshold" of sensitivity which is unacceptable for most sensitive applications. In addition, the jet nozzle must be precisely aligned with the downstream sensing means in order for the jet discharge to symmetrically affect the sensing elements. This feature adds to the difficulty of assembly and manufacture.
Other devices known to prior art are primarily electromechanical in nature, such as rate gyroscopes. Rate gyros involve high speed rotating parts which must be precisely manufactured and assembled, have relatively short lifetimes, require relatively long warm-up times and are relatively expensive.